I knew. if you remember, the first thing I asked to borrow from bsnes was the cart mapping code
but I never found a game requiring that specific part so I was always mapping the whole 70-7f:0000-ffff as SRAM (and, to be fair, I only remembered about this possible source of problems last week).

actually we are also diverging a bit more for SRAM (no "paranoid part" in MESS), but I might consider switching to your approach now that we have finally found issues due to SRAM mapping, and hence I have test cases...

EDIT: improved SRAM mapping for large LoROM carts. As a result, I was able to progress a bit in Tokimeki Memorial (still no text, but the game didn't freeze at the first selection...)

in a few days, when I'm back from a work trip, I'll try to make our SRAM handling the same as bsnes